#include <bits/stdc++.h>
using namespace std;
using ll = long long;

constexpr int N = 5e5 + 5;
int n, m, L[N], R[N];
ll k, a[N];

namespace K1 {
  struct BIT {
    ll t[N];
    inline void add(int x, ll v) {for(; x <= n; x += x & -x) t[x] += v;}
    inline ll query(int x) {ll r = 0; for(; x; x -= x & -x) r += t[x]; return r;}
    inline ll rquery(int l, int r) {return query(r) - query(l - 1);}
  } bit;

  int id[N];
  void Main() {
    iota(id + 1, id + m + 1, 1);
    sort(id + 1, id + m + 1, [](int x, int y) {
      return R[x] < R[y];
    });
    ll ans = 0;
    for(int _ = 1; _ <= m; _++) {
      int i = id[_];
      ll p = bit.rquery(L[i], R[i]);
      if(p < a[i]) {
        ans += a[i] - p;
        bit.add(R[i], a[i] - p);
      }
    }
    cout << ans << "\n";
  }
}
namespace A1 {
  struct BIT {
    ll t[N];
    inline void add(int x, ll v) {for(; x <= n; x += x & -x) t[x] += v;}
    inline void radd(int l, int r, ll v) {add(l, v), add(r + 1, -v);}
    inline ll query(int x) {ll r = 0; for(; x; x -= x & -x) r += t[x]; return r;}
  } bit;

  struct Range {
    int l, r, id;
    inline friend bool operator < (Range A, Range B) {
      return A.r < B.l;
    }
  };
  multiset<Range> S;
  bool ban[N];

  int id[N];
  void Main() {
    iota(id + 1, id + m + 1, 1);
    sort(id + 1, id + m + 1, [](int x, int y) {
      return R[x] < R[y];
    });
    for(int i = 1; i <= m; i++) {
      bit.radd(L[i], R[i], 1);
      S.insert({L[i], R[i], i});
    }
    ll ans = 0;
    for(int _ = 1; _ <= m; _++) {
      int i = id[_];
      if(ban[i]) continue;
      ll p = bit.query(R[i]);
      if(p < k) {
        ans++;
        bit.radd(L[i], R[i], -1);
        ban[i] = 1;
      } else {
        ans += k;
        for(auto it = S.find({L[i], R[i], i}); it != S.end(); it = S.find({L[i], R[i], i})) {
          auto [l, r, id] = *it; S.erase(it);
          if(ban[id]) continue;
          ban[id] = 1;
          bit.radd(l, r, -1);
        }
      }
    }
    cout << ans << "\n";
  }
}

int main() {
  // freopen("kfc.in", "r", stdin);
  // freopen("kfc.out", "w", stdout);
  ios::sync_with_stdio(false);
  cin.tie(nullptr), cout.tie(nullptr);
  
  cin >> n >> m >> k;
  for(int i = 1; i <= m; i++) {
    cin >> L[i] >> R[i] >> a[i];
  }
  if(k == 1) return K1::Main(), 0;
  if(*max_element(a + 1, a + m + 1) == 1) return A1::Main(), 0;
}